Ascension of the Immortal Asura - Chapter 7: Blood Refinement

“A modern online novel writer who had been struggling finds themselves transported into the world of One Piece, becoming a 10-year-old child.After a series of events, Ryuen arrives at Cocoyasi Village. The protagonist possesses the Tori Tori no Mi (Bird-Bird Fruit), Mythical Zoan type, Phoenix form.After undergoing a rebirth (Nirvana), the protagonist's transformation no longer involves turning their hands into wings, and the fruit's power becomes even stronger!From the moment they reach Cocoyasi Village, the protagonist and Nami embark on an adventure, traveling from island to island, indulging in food, drink, and fun. Along the way, they also help the poor by taking from the rich, because, after all, Bellmere’s family is still...”

“The ocean took everything from him—his memories, his past, even his name. When Eddy opens his eyes, he's met with unfamiliar faces and a world that no longer feels like his own. Rescued by Mr. Dand, a kind stranger, Eddy finds refuge in his home. As he navigates this new life, he develops feelings for Artur, Mr. Dand's son. But the past never stays buried. As Eddy's memories begin to resurface, he must confront the truth about his identity and the life he left behind. Will he still want that life back, or will his heart remain with Artur?”

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

One drunken night, my friend blurted out something absurd.“Su-Hyeok, I’ve regressed.”“Regressed?”“Yeah, I’ve returned to the past.”“Are you out of your mind?”“You’re humanity’s only hope.”Then, I was dragged into the tower for real… but who cares?Regressor? Tower? Trials? What are those supposed to be?An overwhelming talent is about to crush everything in its path!